Iodoaniline, complex with

P2i2i2i Z = 4 D, = 1.52 R = 0.07 for 4,811 intensities. This structure is isomorphous with that of the p-hydroxybenzoic acid, p-iodo-phenol, and p-iodoaniline complexes. 

The layer-type packing structure is observed in the complexes with para-isomers of disubstituted benzenes, such as p-iodoaniline [109], p-iodophenol [110], p-... 

In another approach for intramolecular 1,4-carboamination of 1,3-dienes an o-iodoaniline was employed as substrate. The use of an o-iodoaniline in the Pd(0)-catalyzed reaction with 1,3-dienes results in a cychzation in the second step (amine attack on the Tr-aUyl complex) with the formation of indohnes. "" This reaction was already described in 1986 by Dieck and was further developed by Larock. Recently, the reaction was apphed to l-sulfonyl-l,3-dienes, which afforded synthetically useful 2-(sulfonylvinyl)indolines 2... 

Fig. 12a, b. The structure of the a-cyclodextrin p-iodoaniline 3H2O complex with the hydration water molecules omitted. ° = C, O =0, 0 =1, O =N, disordered 0(6)—H group indicated by hatching, 0(3) 0(2) hydrogen bonds drawn as double lines. 

A typical second step after the insertion of CO into aryl or alkenyl-Pd(II) compounds is the addition to alkenes [148]. However, allenes can also be used (as shown in the following examples) where a it-allyl-r 3-Pd-complex is formed as an intermediate which undergoes a nucleophilic substitution. Thus, Alper and coworkers [148], as well as Grigg and coworkers [149], described a Pd-catalyzed transformation of o-iodophenols and o-iodoanilines with allenes in the presence of CO. Reaction of 6/1-310 or 6/1-311 with 6/1-312 in the presence of Pd° under a CO atmosphere (1 atm) led to the chromanones 6/1-314 and quinolones 6/1-315, respectively, via the Jt-allyl-r 3-Pd-complex 6/1-313 (Scheme 6/1.82). The enones obtained can be transformed by a Michael addition with amines, followed by reduction to give y-amino alcohols. Quinolones and chromanones are of interest due to their pronounced biological activity as antibacterials [150], antifungals [151] and neurotrophic factors [152]. 

A one-pot synthesis of 3,3-disubstituted indolines was achieved by taking advantage of a sequential carbopalladation of allene, nucleophile attack, intramolecular insertion of an olefm and termination with NaBPh4 (Scheme 16.6) [10]. First, a Pd(0) species reacts with iodothiophene selectively to afford ArPdl, probably because the oxidative addition step is facilitated by coordination with the adjacent sulfur atom. Second, the ArPdl adds to allene, giving a Jt-allylpalladium complex, which is captured by a 2-iodoaniline derivative to afford an isolable allylic compound. Under more severe conditions, the oxidative addition of iodide to Pd(0) followed by the insertion of an internal olefm takes place to give an alkylpalladium complex, which is transmetallated with NaBPh4 to release the product. 

Here again, the reaction involved an intramolecular displacement of the iodide by an ester enolate (Scheme 10). Preparation of stable azapalladacycle ( )-93 commenced with treatment of sulfonamide 90, accessible via A -alkylation of A -trifluoromethanesulfonyl-2-iodoaniline with palladium(O) (Pd2(DBA)3 DBA = dibenzylideneacetone) and tetramethylethylenediamine (TMEDA) to afford palladium(ll) complex 91. An easy ring closure of complex 91 provided palladacycle ( )-92 in 92% yield via addition of /-BuOK (IM in solution in THE, 1.2equiv) at room temperature. Displacement of tetramethylethylenediamine with triphenyl-phosphine delivered palladacycle ( )-93 in quantitative yield. 

The cyclopalladated Schiff s base 624 reacts with symmetrical alkynes RC=CR [R = Et, C02Me or (EtO)2CH] to give isoquinolinium salts 625 . 2-Phenylcinnolinium salts 627 are similarly formed from the palladium complex 626 and acetylenes k Palladium-catalysed reactions of c -bromo- or o-iodoaniline with terminal alkynes under carbon monoxide pressure give good yields of 4-quinolones (equation 62). ... 

Larksarp and Alper used a palladium(II) catalyzed cyclocarbonylation reaction to generate a series of more complex and biologically relevant 4(3 0-Penicillium chrysogenum), have been shown to exhibit PTK inhibition and cholecystokinin inhibition as well as antimicrobial, anti-convulsant, anti-depressant and anti-inflammatory properties. Reaction of o-iodoaniline, a substituted ketenimine, and carbon monoxide with palladium(II) acetate and l,l -bis-diphenylphosphino-ferrocene (dppf) under thermal conditions gave the desired quinazolinone in near quantitative yield. In the same report, the authors showed that similar reactions could also be conducted with isocyanates and carbodiimides (not shown). 

Palladium nanoparticles, stabilized in micelles formed by polystyrene-co-poly(ethylene oxide) copolymer (PS-PEO) and acetylpyridinium chloride (CPC) as a surfactant, have been used to catalyze heterocyclization of N-methylsulfonyl-o-iodoaniline with phenylacetylene leading to formation of a substituted indole. The activity of the colloidal palladium catalytic system is comparable to that of the low-molecular-we ht palladium complexes, whereas the stabUity of the colloidal palladium system is much h her. The reuse of the catalyst PS-PEO-CPC was demonstrated in experiments with fresh starts as well as by thermomorphous separation of the catalyst from products (20060M154). 

Heterogeneous palladium catalysts have been prepared by covalent immobilization of palladium (11) complexes onto SBA-15 sdica. The heteroannu-lation of 2-iodoaniline with triethyl(phenylethynyl)silane using these preformed palladium complexes gives excellent yields in Larock synthesis of indoles. These palladium catalysts have been demonstrated to be recyclable through multiple recycling experiments (2010MI179). 

Another approach to the construction of five-membered nitrogen heterocycles by way of intermediate jt-allylpalladium complexes involves carbopalladation reactions of 1,3-or 1,4-dienes [85]. For example, Larock has described the coupling of N-tosyl-2-iodoaniline with 1,3-cyclohexadiene, which affords 119 in 87% yield (Eq. (1.48)). The allylpalladium complex 120 is a key intermediate in this transformation. Asymmetric versions of these reactions that generate pyrrolidine products have also been described [86]. Related Heck reactions that employ vinylcyclopropanes as diene surrogates have also been reported, although lengthy reaction times (3-4 days) are often required for transformations of these substrates [87]. 

In 1983, Dieck and co-workers studied the reactions between aryl and vinyl halides with 1,3-dienes and amines. The catalytic formation of n-allylic palladium complexes via addition reactions to 1,3-dienes was involved, then the complexes formed reacted with amines and gave the final products. In order to explore the potential value of this methodology in organic synthesis, they tested 2-iodoaniline as a substrate as well. % using isoprene and 1,3-cyclohexadiene as the coupling partner, the desired cyclized produets were formed in good yields (Scheme 2.80). 

Well-defined palladium complexes are interesting from an academic point of view. In 2013, Shi, Cao and their co-workers prepared a well-defined fer-rocenyl functionalized NHC-palladium complex and applied it as an efficient catalyst for Larock heteroannulation. 2,3-Disubstituted indoles were isolated in good yields (69-90%) with high regioselectivity from the reactions between 2-iodoanilines or 2-bromoanilines and their derivatives with various internal alkynes (Scheme 2.98). The reactions occur in a broad scope and with a high tolerance of functional groups. NHC-palladium complexes could be excellent candidates to replace expensive palladium-phosphine complexes for Larock indole catalysis. 

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